The present invention relates to devices which combine both a connector and a switch for disconnecting an xe2x80x9cantenna circuitxe2x80x9d, in particular of the xe2x80x9cpatch antennaxe2x80x9d type hereinafter referred to as a flat antenna, and circuits for supplying this, whilst connecting these same circuits to a plug allowing external connection of these circuits. This plug is for example itself connected to a cable for supplying an antenna which is more effective than the initial flat antenna. Such devices are for example used for connecting a portable telephone to a fixed base.
Such a currently known device is depicted in its disconnected state in FIG. 1 and in its connected state in FIG. 2.
The flat antenna 101 is fixed to a support 102, as is the earth plane 103 which supplements the antenna in order to obtain the required radiation diagram. The antenna is supplied by a spring connector 104 and the earth plane by a spring connector 105, from circuits for transmitting and/or receiving radio frequency signals which are themselves fixed to a printed circuit board 106.
The radio frequency signal arrives at this printed circuit through a circuit 107 and the earth through a circuit 108. The radio frequency signal is then routed from this circuit 107 as far as a spring connector 104 by means of a switch 109 formed by a spring blade 110 which can, according to its position, provide continuity between the circuit 107 and a circuit 111 on which the spring connector 104 bears.
The continuity between the blade 110 and the circuit 111 is provided by a conductive piece 112 fixed in the insulating body 113 of the switch. A metallic rod 114 perpendicular to the plane of the circuit 106 is fixed to the flexible blade 110.
When a pressure is exerted on the end of this rod, it makes the blade 110 flex and cuts off communication between this blade and the piece 112. The body 113 is itself surrounded by a conductive pot 115 which is connected to the earth circuit 118 in order to be able to obtain the earth recovery as described below.
In the disconnected state illustrated in FIG. 1, the radio frequency signal arrives through the conductor 107, passes through the blade 110, the piece 112, the conductor 111 and the spring connector 104, and is finally applied to the flat antenna 101.
In order to be able to use an external antenna, or possibly a measuring circuit, a plug 116 is used, comprising an external casing 117 and a central conductor 119 forming a core and separated from the conductive external casing by an insulating layer 118.
This plug is conical in shape, so as to be able to enter a hole 120 provided in the support 102 in line with the switch 109 and situated also at the separation level between the flat antenna 101 and the earth plate 103. The end of the central conductor 119 of the plug 116 projects at the tip of this conical part at a hole provided in the external casing 117.
When the plug is lowered in order to insert it in the hole 120, the end of the core 119 presses on the rod 114, which makes the blade 116 flex and interrupts the transmission of the radio frequency signal to the piece 112 and therefore to the flat antenna 101. The radio frequency signal is on the other hand then applied to the core 119 of the plug, so as to be able to be transmitted to the circuits connected to this plug, which are not shown in the figure.
Simultaneously, the conical part of the casing 117 of the plug is placed in a hollow provided in the top part of the conductive pot 115 of the switch 119 and adapted to the conical shape of the end of the plug. In this way contact is established between the casing 117 of the plug and the pot 115 of the switch, which establishes the earth connection between the circuit 108 and the external casing of the plug.
Mechanical means, not shown but known to persons skilled in the art, provide the mechanical fixing of these pieces together.
This system functions well but has the drawback of being of large size and consequently reducing the surface area of the flat antenna, which therefore reduces the performance of the latter.
In order to be able to reduce the dimensions of this system and to be able to increase the surface area and therefore the efficacy of the flat antenna, the invention proposes a connector/switch unit for alternately connecting an earth circuit respectively to an earth plane or to the external casing of a plug, and a radio frequency circuit respectively to an antenna circuit or to the core of said plug, this earth plane and antenna circuit being carried by one and the same insulating support plane comprising a hole for allowing said plug to pass, principally characterized in that the earth circuit is connected to said earth plane by a first spring connector distinct from the switching means of the unit, in that the support plane comprises a hollow cylindrical protrusion comprising an internal cavity opening out in said hole, in that this hole comprises an oval hollow periphery adapted to the conical shape of said plug, in that the antenna circuit and the earth plane are extended towards the inside of the hole whilst matching said oval hollow periphery, and in that the unit also comprises a second spring connector placed in the said internal cavity and comprising a central rod provided with a collar and pushed in one direction by a spring in order to establish contact with the antenna circuit when said plug is removed, and to establish contact with said core by cutting off contact with the antenna circuit when said plug is pressed into the hole, pushing said rod in the other direction.
According to another characteristic, the unit comprises a printed circuit board coplanar with said flat support supporting said earth circuit and said radio frequency circuit; said cylindrical protrusion bearing on the printed circuit board and the second spring connector also bearing on the printed circuit plate at the radio frequency circuit through its end opposite to the one establishing contact with the plug.
According to another characteristic, the extension of the antenna circuit inside the hole is sufficiently long to serve as a stop for the said central rod by means of the collar carried by this central rod.